Moralia [Annotated] (With Active Table of Contents)

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Trekking in Nepal Himalaya, especially operates Nepal local agency specialised Hiking operating company in Nepal Everest Region and after that Annapurna Circuit must be on to do list of adventure people. The Animal Kingdom Park covers … B. K Kingdom of Adventure: INSIVUMEH reported variable activity beginning on 11 April with high levels of explosive activity on 12 April marking the beginning of the sixth eruptive episode of the year, which lasted for three days.

An incandescent fountain persisted m above the crater and fed two lava flows during the event; one traveled 2 km down the Las Lajas ravine, and the other reached 1 km in length in the Santa Teresa ravine. Avalanches were constant along the flanks during this episode. Continuous ash emissions were observed as well; plumes generally rose no higher than 5. On 13 April the ash plume extended km SW from the summit. A brilliant hotspot was observed in satellite imagery on 14 April after which no further VAAC reports were issued until early May.

On 29 April, after more than a week of rain, a lahar descended the Las Lajas drainage but no damage was reported. Activity at Fuego increased significantly during May , and included three eruptive episodes that generated ash plumes, pyroclastic and lava flows, and increased rainfall that resulted in lahars.

Ash plumes rose above 5. Seismic activity increased on 5 May in the form of internal vibrations caused by lava which flowed more than 1. The 7th eruptive episode of the year began on 6 May with incandescent material rising m above the summit crater, causing two lava flows. One traveled down Las Lajas ravine more than 3 km; the second descended the Trinidad ravine for 1.

Block avalanches were constant around the crater rim. The episode lasted for more than 32 hours figure 45 ; the moderate to strong explosions ejected ash to altitudes above 5. Ashfall was reported in Escuintla and its surroundings. There were no pyroclastic flows during this episode. The next eruptive episode 8 did not involve seismic explosive activity figure Instead, several large pyroclastic flows overflowed the crater rim on 18 and 19 May and descended the flanks towards Las Lajas and Honda ravines figure 46 resulting in ashfall reported to the S, SW, and W, in villages more than 30 km away.

A large ash plume reached more than 5. The ninth eruptive episode of generated incandescent fountains m above the summit; they fed a 2-km-long lava flow down the Las Lajas ravine figure Seismic activity began to increase on 21 May and lasted through 23 May see figure Moderate and strong explosions created an ash plume that rose to 5.

A lahar descended the Las Lajas ravine on 20 May and was recorded by the seismic station FG3, but no damage was reported. Activity during June A significant rainfall combined with the plentiful ash from recent pyroclastic flows, resulted in lahars descending Las Lajas and El Jute ravines on 5 June They transported blocks, branches, and tree trunks, and a strong sulfur smell was reported by nearby residents.

Another lahar was reported on 18 June that was 15 m wide and had a 1. An increase in seismic activity during the afternoon of 24 June signaled the beginning of eruptive episode This was followed by about 30 hours of moderate to strong explosive activity that could be heard and felt as far as 12 km away. A dense ash plume on 25 June rose to 5.

Incandescent material rose m above the summit crater during this episode and fed three lava flows; the first descended Las Lajas ravine 2. Seismic activity from episode 10 decreased on 26 June. The scarp of an older edifice, Meseta, lies between m-high Fuego and its twin volcano to the north, Acatenango. Construction of Meseta dates back to about , years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at Acatenango.

In contrast to the mostly andesitic Acatenango, eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in , and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

Large SO 2 plumes and intermittent lava lake during Nyamuragira or Nyamulagira , a high-potassium basaltic shield volcano on the W edge of VVP, includes a lava field that covers over 1, km 2 and contains more than flank cones in addition to a large central crater see figure 54, BGVN A large lava lake that had been active for many years emptied from the central crater in Numerous flank eruptions have been observed since that time, the last during November March on the NE flank.

This report covers the substantial SO 2 emissions from both Nyamuragira and nearby Nyiragongo 15 km SE between November and April , and the onset of eruptive activity, including a new lava lake, at the summit crater beginning in May Activity is described through April On-the-ground information about Nyamuragira is intermittent due to the unstable political climate in the region, but some information is available from the Observatoire Volcanologique de Goma OVG , MONUSCO the United Nations Organization working in the area , geoscientists who study Nyamuragira, and travelers who visit the site.

A substantial flank eruption took place from November through March This was followed by a period of degassing with SO 2 -rich plumes, but no observed thermal activity, from April through April Increased seismicity and minor thermal activity was observed at the central crater during April ; lava fountains first seen in early July continued through September. A lava lake in the crater was confirmed on 6 November , and it produced a consistent and strengthening thermal anomaly through the first week of April , when it stopped abruptly. Thermal activity suggesting reappearance of the lava lake began again in early November , and strengthened in both frequency and magnitude into early January , continuing with a strong signal through April Activity during November March Lava fountains up to m high produced flows that advanced nearly 12 km N in the first 10 days.

Three scoria cones formed adjacent to the fissure during the eruption, and a small lava lake appeared in the center of the largest cone. During January , lava flowed from the vent area and from numerous small breakouts within 2 km of the cones figures 58, Dario Tedesco reported that the eruptions ceased in March after a series of explosion earthquakes recorded by the OVG had ended; the last MODVOLC thermal alert in the area of the eruption was captured on 14 March , and none were reported again until Activity during April May Since , observations of the crater have also been done once or twice a month by helicopter.

This area is a high-risk sector due to the presence of armed groups, and it is impossible, due to the lack of security, to make detailed field surveys Coppola et al. A progressive collapse of the m-wide, m deep pit crater located in the NE part of the caldera began as soon as the eruptions ended. They noted that during the second half of April, large SO 2 plumes continuously emerged from the pit crater. The plumes represent combined emissions from both Nyamuragira and Nyiragongo, which are too close together to distinguish the source in the satellite data.

Beginning in April elevated values occurred more than 20 days per month through December Values were more variable in both frequency and magnitude during with a notable surge of activity during June that resulted in daily SO 2 plumes. Details of monthly SO 2 values are given in the last section of this report see table 3. Activity during June April Incandescence at the summit and increased seismicity was reported again in April , along with increasing SO 2 values.

An extended series of MIROVA thermal anomaly data beginning in May clearly shows the episodic periods of active heat flow at Nyamuragira from late May through April figure During the first episode, from late May to early September , lava fountains were observed in early July, and reported to be active through September BGVN Campion and Smets and others debated whether the lava lake first appeared in April or not until November.

On 6 November a small lava lake was confirmed at the base of the summit pit when sighted during an OVG helicopter survey. Thermal anomalies were persistent throughout , with a noted increase in both frequency and magnitude during July figure 62 C. MONUSCO-supported summit crater visits by researchers on 2 April , and photographer Oliver Grunwald on 10 July , confirmed the presence of an active lava lake during both visits figure 64, and video link in Information Contacts.

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This was followed by a period from early June through early November with no record of activity at Nyamuragira. A new pulse of thermal activity, with values similar to those observed during July April , reappeared in early January figure 62 E and continued through April On an OVG-sponsored visit to the summit crater on 11 March , independent journalist Charly Kasereka photographed the summit crater with incandescent lava covering the crater floor figure Sulfur dioxide and thermal anomaly data.

Abundant sulfur dioxide emissions at Nyamuragira during November April show large variations in both magnitude and frequency during the period table 3. A plot of the SO 2 data figure 67 reveals a sharp increase in both the number of days per month with DU greater than 2 and the actual maximum DU value during the active flank eruption between November and February After lower values during March , they rise steadily and remain significantly elevated for all of Values drop briefly in early and then rise again during April , remaining elevated through February before dropping off significantly.

A similar plot of the number of monthly MODVOLC thermal alert pixels for Nyamuragira from November through April figure 68 shows that there were no thermal alerts for the period from April February when SO 2 emissions were large and frequent. In contrast, there were frequent thermal alerts from June April when SO 2 emissions were also high.

Data represent minimum values due to OMI row anomaly missing data gray stripes , and missing days. The gas is measured in Dobson Units DU , the number of molecules in a square centimeter of the atmosphere. If you were to compress all of the sulfur dioxide in a column of the atmosphere into a flat layer at standard temperature and pressure 0 C and Bull Volcanol Detailed multidisciplinary monitoring reveals pre- and co-eruptive signals at Nyamulagira volcano North Kivu, Democratic Republic of Congo.

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Bull Volcanol 76 Spatio-temporal dynamics of eruptions in a youthful extensional setting: Insights from Nyamulagira volcano D. Congo , in the western branch of the East African Rift.

Earth-Science Review , Africa's most active volcano, Nyamuragira, is a massive high-potassium basaltic shield about 25 km N of Lake Kivu. Also known as Nyamulagira, it has generated extensive lava flows that cover km2 of the western branch of the East African Rift. The broad low-angle shield volcano contrasts dramatically with the adjacent steep-sided Nyiragongo to the SW. The summit is truncated by a small 2 x 2. Historical eruptions have occurred within the summit caldera, as well as from the numerous fissures and cinder cones on the flanks. A lava lake in the summit crater, active since at least , drained in , at the time of a major flank eruption.

Historical lava flows extend down the flanks more than 30 km from the summit, reaching as far as Lake Kivu. The largest historical eruption took place in November and generated a km-high eruption cloud, pyroclastic flows that traveled 8 km, and several lava flows. This report briefly summarizes activity between and June , and covers details of activity from July through December Summary of activity.

Intermittent activity including pyroclastic flows, ash plumes, lava flows and explosive events took place between and Since July there have been persistent gas-and-ash plumes, dome growth, and both pyroclastic and lava flows.

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Moralia [Annotated] (With Active Table of Contents) - Kindle edition by Plutarch, Ralph Waldo Emerson, William Watson Goodwin. Download it once and read it. Results 1 - 16 of Moralia [Annotated] (With Active Table of Contents). 14 Sep by Plutarch and Ralph Waldo Emerson.

Lahars are also very common in this high-rainfall area, and cause damage to infrastructure on a regular basis. A lava dome was first observed growing in September within the crater that formed during the eruption. By July , it had reached the height of the highest part of the crater rim; by January it filled the crater and formed a new summit, m above the E rim. This led to lava blocks travelling down the flanks, in addition to the lava flows and pyroclastic flows traveling down the flanks of the cone inside the crater during A summary of thermal anomalies compiled from MIROVA data figure 46 demonstrates the ongoing but intermittent nature of heat flow between and Summary of June December activity.

Activity was very consistent throughout the period of June through December The thermal webcam captured images of lava flows, pyroclastic flows and ejected incandescent blocks nearly every month. Satellite imagery of hot spots were common as well. The Washington VAAC reported observations of ash plumes every month, although they generally rose only to altitudes below 5. IG reported seismicity as varying between moderate and high during the period. Activity during June-December Activity during June was characterized by numerous explosions and small pyroclastic flows that descended the flanks of the cone.

A pilot reported an ash plume on 11 June rising 2. Weather generally obscured satellite views. On 19 June, multiple small emissions of volcanic ash were seen in the observatory webcam along with incandescent material on the flanks. IG noted ash emissions on 2, 4, , 18, , and 27 July rising m to 2 km above the summit. The Washington VAAC issued a report of hot spots visible in satellite imagery on 1 August and a pilot report of an ash plume at 6. IG reported lower level plumes m above the summit with minor ash on 6 other days during the month.

Activity increased during September On 2 September, ash plumes were observed extending about 45 km W of the summit at 5. Another faint plume of volcanic ash was observed within 20 km of the summit the next day. An ongoing hotspot with possible small ash emissions was noted on 4 September. A thermal camera detected an explosion on the following day that also included ballistics. Steam plumes with minor ash rose to around 1 km above the summit and dispersed generally W several times during the month.

An additional single pixel thermal alert was issued on 25 October, and a three-pixel alert appeared on 29 October. IG reported steam-and-ash plumes rising up to 1 km above the summit a few times during the month, which were visible on the rare clear-weather days figure The Washington VAAC, however, issued reports during , , and 27 November of possible low-level ash-bearing plumes.

On 5 December a webcam recorded a steam-and-gas emission associated with an incandescent lava flow on the E flank. The largest plume, on 14 December, rose to 6. IG reported moderate seismicity and low-level steam plumes with minor ash content on several occasions. Moderate seismic activity continued during January with low-level steam-and-ash plumes from explosions rising a few hundred meters above the summit, according to IG.

A larger explosion reported by IG on 16 January generated an ash plume that rose 2 km and drifted SE. Their reports were of small puffs of ash within a kilometer of the summit drifting for a few hours before dissipating. Steam plumes containing minor amounts of ash were recorded a few times during February during periods of moderate seismicity. The Washington VAAC issued several reports, during , , , 24, and February, noting occasional plumes with ash rising to less than one km above the summit, and hot-spots seen in satellite imagery on , 17, 19, and 27 February.

An aircraft reported volcanic ash on 19 February at 6. A new lava flow first observed on the SW flank on 11 February had advanced 1 km by 19 February. Single pixel alerts were issued on 7, 19, and 23 February as well. The webcam captured a hotspot at the summit on 11 March. A thermal camera image of a lava flow taken on 13 March showed the visible part of it to be over m long figure 49 , and IG noted in their 13 March report that is was actually about 1.

Activity during April included moderate seismicity and incandescence at the crater reported by IG. A lava flow on the SW flank was visible with the infrared camera during the first week; this agrees with the 5-pixel MODVOLC thermal alert recorded on 5 April and the bright hotspot observed in both satellite imagery and the webcam during April. Hot spots were observed via satellite and webcam several additional times during the month. Additional thermal alerts also appeared on 10 and 21 April. Steam-and-ash plumes rising to 1 km above the summit were intermittent throughout the month, mostly observed from the webcam.

In a special report issued on 19 May, IG noted a new lava flow during the previous week that descended the S flank, forming a fan with three lobes on the SE and SW flanks. The length was greater than 1, m from the summit on 19 May, although the flows remained on the flanks of the summit cone within the caldera figure IG noted an increase in emission tremor on 17 May which may have been related to the extrusion of the lava, but weather conditions prevented visual confirmation.

During May, intermittent low-level gas-and-ash plumes within 15 km of the summit were reported on most days. Nonetheless, thermal images showed lava flows down the SW and S flanks of the cone several times, and hot spots were observed in satellite images and on the webcam when the weather permitted. Steam-and-ash plumes were generally reported to rise to 1 km or less above the summit and drift usually NW or SW within 15 km of the volcano. A pilot reported volcanic ash on 30 June at 6.

IG issued a special report on 24 June noting increased seismicity in the form of increased tremor signal and explosions on 23 June. The thermal camera located in the area of El Copete, 5 km S of the crater, showed an increase in surface activity characterized by several lava flows on the SW, S, and SE flanks exceeding one km in length figure Seismic activity was reported as high during July by IG, and included explosions, tremor, long-period earthquakes, harmonic tremor, and emission signals.

During the first week, incandescent material was visible more than 1 km down the SE flank in thermal images. On 17 July, light gray deposits possibly from a pyroclastic flow were observed; on 21 July explosions again ejected incandescent material onto the flanks. Steam and ash emissions were intermittent and generally remained below 5. High levels of seismic activity continued during August Other plumes that were reported by pilots on 25 August at 8. Ash-and-gas emissions were reported by the Washington VAAC during 14 days in September , generally drifting N and W at altitudes less than 2 km above the crater 5.

The Guayaquil MWO reported volcanic ash at 6. Puffs of ash seen in the webcam were reported at 7. Continuous emissions were observed in the webcam during October, generally below 4. Continuous emissions appeared again on 30 October at 5. During the last two weeks of November , steam, gas, and ash emissions rose to less than 2 km above the summit and incandescent blocks rolled m down the flanks of the cone. VAAC reports noted hotspots in satellite imagery on 7 December. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis.

A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical eruption took place in , producing a km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

A February ash explosion of Columbia's Nevado del Ruiz volcano was the first confirmed ash emission in over 20 years. The broad, glacier-capped volcano has an eruption history documented back 8, years, and historical observations since Notably, a large explosion at night in heavy rain on 13 November generated large lahars that washed down 11 flank valleys, inundating most severely the town of Armero where over 20, residents were killed.

It remains the second deadliest volcanic eruption of the 20th century after Mt. Pelee in killed 28, Summary of activity, November June After the large explosions and deadly lahars of November , activity at Ruiz continued with intermittent ash emissions and significant seismic activity through July Seismicity, deformation, and SO 2 emissions have been closely monitored since the eruption. Between and February intermittent high-frequency seismic events earthquake swarms were recorded, but no ash emissions were observed.

In September , seismicity notably increased in frequency and diversity of event type until early when fresh ashfall was observed. During March, long-period seismicity underwent a fold increase. SO 2 emissions also dramatically increased between March and June An ash plume that rose to 11 km altitude on 29 May caused ashfall in over 20 communities to the NW and closures at three nearby airports.

Widespread ashfall during June covered solar panels on field equipment. An EO-1 satellite image from 6 June shows a plume and significant ashfall around the summit figure Summary of activity, July December Explosions and seismic tremor with ash emissions continued during July and August Ashfall was reported within 30 km on numerous occasions.

From September through early July minor amounts of ashfall were reported a few times each month, mostly in the immediate vicinity of the volcano. After a larger explosion on 11 July , sparse and intermittent ash emissions were reported between August and April Between May and October there were no reports of ash emissions or thermal anomalies. A significant increase in seismicity occurred during the second week of November , and ash was seen at the summit during an overflight on 19 November. Ash fell in communities within 30 km several times each month through December Seismic evidence suggesting possible lava dome extrusion first appeared in August , and stronger signals were recorded on 22 October.

Thermal anomalies around the summit crater increased in frequency and magnitude during the last three months of Activity during July October A large ash plume on 30 June prompted evacuation warnings to several communities within 30 km and closed three nearby airports for the second time within 30 days. SGC noted that explosions and ash emissions continued throughout the month in spite of a decrease in seismicity.

Ashfall was reported near the volcano, and in municipalities in the departments of Caldas W and Risaralda SW , steadily throughout the month. Tremors associated with continuing gas and ash emissions occurred throughout August ; ash plumes were observed rising m above the summit crater. On 12 August, a gas-and-ash plume observed with a webcam rose 1 km above the crater and drifted W, and ashfall was reported in Brisas 50 km SW.

Webcams showed gas-and-ash plumes rising m and drifting W and NW during August. Minor amounts of ashfall were reported by SGC in areas around the volcano each month during September through 11 July table 4 , when a larger ash emission occurred. A noted increase in seismicity beginning on 13 April was also reported by SGC. Multispectral imagery showed the plume extending 55 km NW.

Ash emission events at Ruiz during September July Data compiled from various sources as shown. Evidence for ash emissions between August and April is sparse and intermittent. The SGC Monthly reports during this time mention pulses of low-energy tremor associated with emissions of gases, steam, and small amounts of ash every month except November, when they reported only steam and gas, but no specific dates are given. SGC's Technical Information Monthly reports mention occasional grayish coloration, suggesting ash in the gas-and-steam plumes during August-October Tremors associated with small amounts of ash and grayish coloration in the plumes are again noted from January through April without describing specific events.

They note in weekly reports for and December that gray emissions possibly associated with ash in plumes of mostly water vapor and gases were observed. During the week of December they recorded low-energy tremors associated with the output of small amounts of ash, which were reported in trace quantities in Manizales.

In their 31 December January and February weekly reports they noted the occurrence of tremors associated with ash and gas. There is no mention of ash in their March or April weekly reports. The MIROVA thermal anomaly data do show minor thermal anomalies in latest August and more persistent anomalies at the beginning of October figure 73 prior to the reports of ash emissions during November.

Activity during November December A significant change in seismicity occurred beginning in the second week of November There was an increase in the number of long-period LP earthquakes, pulses of volcanic tremor, and several periods of continuous tremor lasting for hours or even days associated with fluid movement, and with emissions of gas and ash table 5. Several of these periods were preceded by an LP event. The first significant pulse of volcanic tremor began on the evening of 18 November following an LP event and lasted more than 12 hours.

Periods of continuous tremor associated with ash emissions at Ruiz during November Some of the tremor episodes were preceded by long-period LP events. Ash emissions were also verified in satellite imagery figure 74 and by reports from nearby communities. Ash was again observed on the N side of the Arenas crater on 29 November in the early morning after a lengthy period of continuous tremor was recorded the previous day see table 5. During the second half of December , SGC reported significant concentrations of ash in the emissions that were associated with continuous tremor episodes.

On 15 December seismic signals indicating ash emissions were detected, and then confirmed by a local webcam and nearby residents. The next day they reported a narrow plume of minor volcanic ash extending 22 km SW of the summit at 6. A faint thermal anomaly was also detected. A satellite image taken on 26 December clearly shows ash deposits in nearly all directions from the Arenas crater figure SGC reported seven episodes of continuous tremor on 4, 7, 14, 24, 26, 28, and 29 January, almost all of which were associated with ash emissions figures Ashfall was reported several times after these episodes in the Eje Cafetero area to the W of Ruiz.

Occasional minor ash emissions were reported during February during periods of continuous tremor, but most of the emissions were steam and gas. Although seismic tremors were diminished during March from the previous month, emissions associated with these tremors contained gases and minor amounts of ash from 8 March through the end of the month. An increase in several types of seismicity was observed by SGC during April Volcanic tremor, associated with gas and ash emissions, were confirmed through photographs taken by the webcams figure 77 , and by officials at PNNN and SGC.

The Washington VAAC reported a small puff of gas and minor amounts of ash visible in satellite imagery on 22 April at 7. Ash emissions were photographed by the webcams located in the Azufrado and Cerro Guali regions on at least eleven dates during May The Washington VAAC reported possible emissions on 19 and 26 May, but extensive weather clouds prevented satellite observations.

Most of the frequent episodes of volcanic tremor during June were also associated with ash emissions which were photographed at least six times during the month. A significant increase in ashfall was reported during July figure 78 , including in the regions of Caldas, Tolima, and Risaralda, as well as by officials in the Park PNNN. The Washington VAAC noted ash emissions visible in satellite data and the webcam on 13 July, with a plume at 7 km altitude drifting NW a few tens of kilometers before dissipating.

Seismic signals indicating emissions were reported on 23 July and observed in the webcam, according to the Washington VAAC. SGC noted seismic tremors and a plume on the morning of 26 July that rose to 3 km above the summit 8. Seismic data indicated continued occasional bursts of ash drifting W to WSW during the next few days. A bright thermal anomaly was reported in satellite imagery on 31 July, but no ash was observed. SGC reported greater instability at Ruiz compared with previous months during August Seismicity related to fracturing and fluid flow both increased during the month.

Energy levels for spasmodic tremor related to gas and ash emissions were also generally higher. They noted another possible plume with minor ash on 12 August at 6. A brief emission containing minor ash on 28 August, observed in a webcam, was reported by the Washington VAAC as extending about 35 km W. Ongoing emissions rising a few hundred meters above the summit with occasional small bursts of ash continued for the next two days. A news article reported that the La Nubia airport closed that day due to ash emissions. Most ash emissions during the month affected the regions of Caldas and Risaralda NW of the volcano.

Plume altitudes ranged from 5. Incandescence observed in a webcam on 4 September was followed by a high-energy tremor. Ash was moving to the NW below 5. Ongoing emissions with small bursts of ash continued through 15 September with a new emission to 7. The OVSM reported a strong seismic signal at on 17 September, but weather clouds blocked observation from satellite imagery of the potential ash plume.

The largest tremor of the month occurred in the afternoon of 18 September and ash emissions were verified in the webcams as well as by SGO officials doing fieldwork in the area; ash emissions were also observed in the webcam on 19 September at SGO reported a seismic event on 22 September that produced water-vapor, gas, and ash plumes that rose 2 km above the crater and drifted mainly NW.

An advisory issued on 29 September noted ash to 8.

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A gas, steam, and ash plume rose 1. Another report of volcanic ash early on 9 October was not visible in satellite imagery, although a thermal anomaly persisted and seismicity was elevated. A small ash emission was spotted in imagery data drifting WNW late on 9 October. A discrete emission of ash rose to 9. SGC first noticed an unusual pattern of seismicity known as a "drumbeat" signal, for which they issued a special report on 20 August The "drumbeat" signal is characterized by discrete episodes of short duration about 30 minutes each that repeat at regular time intervals and show similar waveforms and energy.

They are interpreted by volcanologists to represent phenomena associated with the ascent of high-viscosity magma to the surface and thus are an indicator of near-surface extrusion or dome building. SGC recorded the same signal on 8 September, and then again on 22 October figure Thermal anomalies near the Arenas crater were observed by SGO on 26, 28, and 30 September, and were again recorded on 7, 9, and 10 October Seismic activity decreased slightly during November , but there still were episodes of volcanic tremor associated with gas and ash emissions that were recorded by the webcams and personnel at PNNN.

Continuous tremor signal was recorded on 1 and 4 November. The "drumbeat" signal was again briefly recorded on 13 November. Thermal anomalies increased in frequency and were observed on 4, 18, 20, 22, 26, and 27 November. SGC confirmed ash emissions on 5, 10, 14, 27, and 29 November. SGC captured images of the ash plume from two different webcams figure They were recorded on 3, 22, 26, and 31 December.

Additionally, the MIROVA thermal anomaly system showed significant increases in anomalies at Ruiz during the last three months of figure Minor episodes of volcanic tremor with ash emissions were reported by SGC during the first two weeks of December A significant volcanic tremor with ash emissions occurred on 20 December, and ashfall was reported by SGC officials, PNNN personnel, and residents near the volcano and in the city of Manizales. A gas, steam and ash plume rose 1.

Sulfur Dioxide emissions, June Persistent, large SO 2 plumes were captured from Ruiz many times during June December figure 84 and Dobson Units are the number of molecules in a square centimeter of the atmosphere. If you were to compress all of the sulfur dioxide in a column of the atmosphere into a flat layer at standard temperature and pressure, one Dobson Unit would be 0. Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers more than km2.

The introduction of power electronics technology introduced new conditions of power theory. This is because electronic power converters may bring out reactive power as well as harmonic current from power networks. Thus, the conventional power theory based on average and RMS root mean square values [ 9 ] of voltages and sources cannot be applicable to the analysis and design of power converters and power networks.

The researches [ 11 — 13 ] presented the basic concepts to control the reactive power in order to compensate it. In [ 14 ], the theory defines a set of instantaneous power in the time domain. This theory is focusing on a three-phase circuit, and it always considers three-phase systems together, not as a superposition or sum of three single-phase circuits. This section presents a recapitulation of the scattering bond graph and also gives a more general standpoint of its use.

As mentioned in [ 3 ], system description requires knowing its elements and interconnections. In order to model any physical system, it is necessary to define the system boundary. In case of a boundary breaking up the system into two subsystems, the interaction between subsystems can be described by a duplex pair of oppositely directed signals. Whatever bond exists between two parts of a system may be equivalently represented as a pair of directed signals. The forewave and backwave have been addressed in [ 3 ].

Two systems A and B are joined by a single line, which represents the interaction of the two waves. There is a power exchange between the two systems; part of the complete power could be moving from A to B and part from B to A. Figure 1 shows this interaction between the two systems. If is defined as the net power flowing from A to B, then is defined as the fore-power and as the back-power. Each of these bilateral power flows represents the integration at the port of a scattering flux, which is defined as the product of local scattering density and local velocity of energy propagation.

As the forewave and backwave have units of root power, they can be represented using a single power bond. The net power flow is considered positive in the fore-direction. Then, the net power can be expressed as a function of the waves as follows: Equation 1 shows the relationship between the scattering variables and the normalized effort and flow variables.

In this paper is proposed the graphical representation of the scattering bond as shown in Figure 2. The forewave and backwave are called incident and reflected waves, respectively as it was made in [ 4 ]. The bold half-arrow indicates the sense of the incident wave, while the double half-arrow the sense of the reflected wave. The junction, ports, and elements have the same representation as in a traditional bond graph; only their mathematical relations change.

Figure 3 shows the basic elements used in order to formulate a StBG. The source elements and give their variable for voltage and for the current via the incident wave. These sources can be visualized from an energetic conservation point of view [ 6 ], by using the relationship given in 1. Then, the sources of effort and flow can be interpreted as four scattering sources.

Table 1 summarizes these sources. The relations shown in Table 1 make references to an electrical circuit because voltage and current variables have been considered as the effort and flow, respectively. It is important to note that the combination of these four sources arises because the incident wave defines the sign convention. The scattering variables , are defined at each port of the system and always adopt the positive power convection in a system. As shown in Figure 3 , the constitutive relation for , , and elements is normalized by a resistance.

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The normalization by corresponds to an internal resistance or impedance considered in a system i. This resistance makes it possible to quantify the power transferred between two systems. By considering a linear capacitance , the relation between and is given by , where is the normalized resistance and is the impedance of the element: From this impedance and the scattering relation given between two ports, it is simple to find the relation shown in Figure 3 by replacing the operator by.

The constitutive relation of this element contains a zero in the right half-plane and is nonminimum phase element, although, clearly, it is normally considered to be physically real.

Annotated Table of Contents – J. Michael Rifenburg

The compliance element is obtained in the same manner. Then, when , is zero in both cases and the resistor is said to be perfectly matched [ 3 , 17 — 19 ]. This paper is focusing on single-phase AC circuits; nevertheless, the StBG can be used in all physical systems including those that do not have alternate input sources. Electrical power systems commonly use an impedance load connected to a source so that the analysis can be simplified by using the phasor concept.

This concept focuses on complex values having a magnitude and a phase in order to calculate the power using those vector quantities. In the bond graph methodology, the impedance element has already been formulated [ 19 ]. In this publication, another element besides the nine basic elements is proposed as the impedance element, namely, -element. With the use of this -element, the notion of the interaction between different elements is lost because two or more basic elements can be grouped into one.

Next is proposed the use of the scattering bond graph in order to keep close to the structure of the analyzed circuit. Later, two basic examples of a single-phase electrical system are presented. The basic AC electrical circuit is composed only of a resistive load connected in parallel to the alternative voltage source. Figure 4 shows the StBG of the circuit. As shown in Figure 4 , the two variables in each scattering bond are the incident and the reflected waves ,.

The mathematical formulation is made by considering the relations given earlier and is as follows. The source MSe and the element have the mathematical relations given by 2 and 3 , respectively. As the two components are joined by a 1-junction , the scattering relation corresponds to. Then, considering these relations, the incident and reflected waves in each scattering bond are given by. Equations 5 and 6 represent the scattering waves of the StBG of Figure 4 ; they do not match the traditional effort and flow present in a bond graph.

In any case, the original variables of effort and flow can be recovered [ 6 ] from the new variables using 1. The objective to use the scattering variables is to obtain the active and reactive power directly by regarding the incident and reflected waves. Then, the power delivered by each element is given by where is the total power and and are the incident and reflected power, respectively. By substituting 5 in 7 , the total power dissipated by the element is calculated as follows: The parameters used for the simulation are source and.

Figure 5 shows the incident and reflected waves in each scattering bond. The responses and correspond to the source MSe and and to the resistive -element. It is shown that responses are the same for the two elements from the point of view of magnitude peak of the sinusoidal curves. The source incident wave has a maximum value of The same is the case for the scattering variables of the -element. The values obtained by a traditional analysis do not match these values; hence, the scattering variables are used. The effort and flow responses match exactly the expected values for the voltage and current if a traditional bond graph is used.

As mentioned earlier, the objective to use the scattering variables is to deal with the active and reactive power directly in the StBG.

Figure 7 shows the power responses for the -element. The instantaneous power is presented in Figure 7. As expected, the frequency of the instantaneous power is twice the frequency of the input source. The reflected power is smallest compared with the incident power. Actually, the total power is slightly lower than the incident power because the reflected power is subtracted.

Generally, the average value of the instantaneous power is considered Figure 8 as the power delivered or absorbed by each element. In conclusion, it is observed that the incident power is slightly higher than the total power and the reflected power has a very small value. From this result, it can be concluded that the incident power has a correspondence with the active power in an electrical circuit, the reflected power has a correspondence with the reactive power, and the apparent power can be related to the total power.